SecItemCopyMatching返回空字典

Question

出于某种原因，我在OSX 10.8.4上调用SecItemCopyMatching时得到一个空字典。相应的项目位于钥匙串中，包含用户名和密码。 SecItemCopyMatching创建它（errSecSuccess）但结果字典只包含0个条目。我希望它至少有用户名和密码数据，所以我的请求有什么问题？

OSStatus status;
NSMutableDictionary *query = [NSMutableDictionary dictionary];
[query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
[query setObject:(id)kSecReturnAttributes forKey:(id)kCFBooleanTrue];
[query setObject:@"MyService" forKey:(id)kSecAttrService];

CFDictionaryRef dictRef = NULL;
status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&dictRef);
if (status != errSecSuccess) {
    CFStringRef errorRef = SecCopyErrorMessageString(status, NULL);
    NSLog(@"%s: %@", __FUNCTION__, (__bridge NSString *)errorRef);
    CFRelease(errorRef);
    return nil;
}

// --> dictRef empty

if (dictRef != NULL) CFRelease(dictRef);

Answer 1

请求中有错误。我把关键和对象搞混了。

[query setObject:(id)kSecReturnAttributes forKey:(id)kCFBooleanTrue];

必须是

[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];

然而，正如bdash指出的那样，它只返回非加密属性，如用户名。要获取密码，需要传递

的其他请求

[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];

所以我现在在这里：

OSStatus status;
NSMutableDictionary *query = [NSMutableDictionary dictionary];
[query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];
[query setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
[query setObject:@"MyService" forKey:(id)kSecAttrService];

// get username
CFDictionaryRef dictRef = NULL;
status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&dictRef);
if (status != errSecSuccess) {
    CFStringRef errorRef = SecCopyErrorMessageString(status, NULL);
    NSLog(@"%s: %@", __FUNCTION__, (__bridge NSString *)errorRef);
    CFRelease(errorRef);
    return nil;
}

NSString *username = (__bridge NSString *)CFDictionaryGetValue(dictRef, kSecAttrAccount);
CFRelease(dictRef);

// get password
[query removeObjectForKey:(id)kSecReturnAttributes];
[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
CFDataRef dataRef = NULL;
status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&dataRef);
if (status != errSecSuccess) {
    CFStringRef errorRef = SecCopyErrorMessageString(status, NULL);
    NSLog(@"%s: %@", __FUNCTION__, (__bridge NSString *)errorRef);
    CFRelease(errorRef);
    return nil;
}

NSString *password = [[NSString alloc] initWithData:(__bridge NSData *)(dataRef) encoding:NSUTF8StringEncoding];
CFRelease(dataRef);